Why do some people develop an orange peel effect on their skin from a retinoid? (Photo)

Hi, I have been using a retinoid for a week and a half now. So far, it has done wonders on my closed comedones, but I'm nervous about what it's doing to my pores. They look a lot mkre defined, and after reading horror stories on the internet about people who develop large pores, I wanted to ask the experts. Have i nit been moisturizing enough? I was using one with salycilic acid in it. Now I am trying CeraVe to keep moisture in. Any advice or even knowledge on this subject would be great, thanks